Principia YxK

Principia software is designed to correctly represent all dates and is Y0K,
Y1K and Y2K compliant.

Y0K

Dates prior to 1 AD are correctly represented. 1 BC is treated as year 0, 2 BC
is year -1, and so on. The Julian Proleptic Calendar is used for all
these dates. Dates prior to Julian day 0 (January 1, 4713 BC) are supported.

Y1K

Dates prior to October 4, 1582 are assumed to be in the Julian Proleptic
Calendar, while dates after this date is assumed to be in the Gregorian
Calendar. Note that October 5, 1582 in the Julian Calendar corresponds to
October 15, 1582 in the Gregorian Calendar.

Y2K

There is nothing curious about the year 2000. Dates in the future are correctly
represented until the next calendar correction is introduced. It is unlikely
that such a correction will be introduced for many centuries.